Injection molding apparatus having a nozzle carrying plate

ABSTRACT

An injection-molding half-mold has a base plate ( 1 ), a nozzle-carrying plate ( 2 ), a cavity-carrying plate ( 3 ), and a hot runner ( 4 ) to which there are associated a plurality of resistive elements ( 6 ) connected externally to a power supply source via at least an electric conductor ( 9, 19 ) lead connected to an appropriate external connector. The nozzle-carrying plate ( 2 ) can be removed from the hot runner ( 4 ) without any need for either the electric conductor lead ( 9, 19 ) or the connections of the latter to the resistive elements ( 6 ) to be disconnected

BACKGROUND OF THE INVENTION

The present invention refers to the main component parts of an injectionmold adapted to enable a plastic substance in its fluid, i.e. moltenstate, usually just after the extrusion thereof, to be injected intoappropriate cavities for forming related preforms. In particular, thepresent invention applies, in a preferred manner, to machines adaptedfor molding a plurality of plastic articles at the same time, ie. theso-called “preforms” that are intended for subsequent processing by blowmolding into appropriate final containers, especially plastic bottles.

Although reference will be made in the following description, mainly forreasons of greater descriptive convenience, to a machine for mouldingpreforms of plastic material, as this is used in combination with thepreliminary steps of melting and extrusion of said plastic material, itwill be appreciated that the present invention shall be understood asapplying also to other kinds of uses or applications, as far as thesefall within the scope of the appended claims.

It is generally known in the art that, during the preform moldingoperation, use is generally made of a molding machine comprising astationary half-mold, which is firmly joined to the structure of thesame machine, and a moving half-mold, which preferably moves in avertical direction and is selectively closable into an appropriateposition against the stationary half-mold.

In prior-art solutions, the stationary half-mold usually comprises abase plate 1, a nozzle-carrying plate 2, a cavity-carrying plate 3, atleast a hot runner 4, a plurality of nozzles 5, a plurality of resistiveelements 6 associated with the hot runner, and a plurality of resistiveelements 7 associated with the nozzles 5.

The nozzle-carrying plate 2 is in the shape of a U turned upside down,and is arranged in an intermediate position between the base plate andthe cavity-carrying plate. This is illustrated in FIGS. 1 and 2, whichare views of the three different plates in assembled and separatedpositions thereof, respectively.

The resistive elements 6 are connected to a power supply source (notshown) via a respective plurality of electric conductor leads 9. Eachone of them is furthermore inserted in a wall of the nozzle-carryingplate and passes therethrough, coming out on the outside thereof, whereit is connected to a respective terminal clamp of an appropriateconnector 14.

The resistive elements 7 that are associated with the nozzles 5 in thenozzle-carrying plate 2 are in turn connected to a power supply source(not shown) via a respective plurality of electric conductor leads 11,connecting the respective resistive element 7 to a respective terminalclamp comprised in the same connector 14 that already connects theabove-described electric conductor leads 9.

It is therefore obvious that each one of the electric conductor lead 11is contained, as shown in the Figures, in the body of thenozzle-carrying plate 2.

All this is anyway largely known to ail those skilled in the art and isonly reviewed here shortly in order to more effectively introduce thetechnical context which the present invention actually refers to.

During the practical use of the mold, there are quite frequentlyoccurring such operating conditions as to make it necessary for accessto be gained most conveniently and easily, as well as with a maximumextent of freedom in intervening, to the hot runner or the nozzles. Inthe majority of the cases, these operating conditions are brought aboutby the maintenance needs of the hot runner, e.g. due to a failed heatingelement requiring replacement, or due to a nozzle having plugged up, or,more simply, due to the hot runner itself needing to be cleaned up andcleared of slag and scum depositing therein after a prolonged use.

In all those circumstances in which the nozzle-carrying plate 2 must bedisassembled and separated from the hot runner, the need logicallyarises for all conductor leads 9 to be first disconnected fromrespective terminal clamps (not shown) in order to be able to disengagethe nozzle-carrying plate 2 from the hot runner and then remove theplate 2. However, the disconnection of all the terminal clamps involvedin such an operation is considerably time consuming, i.e. requires a lotof time during which the whole plant must of course be kept at astandstill, ie. inoperative.

Upon conclusion of the planned maintenance or similar intervention, thereverse operation must be then carried out to re-connect all theconductor leads to respective terminal clamps. This obviously requires afurther lot of time and, therefore, this puts a further downtime penaltyon the whole plant.

In other words, such operations of disconnecting and reconnecting theabove cited conductor leads, which are inherently rather long anddelicate to carry out, demand a considerable extension of the machinedowntime and an equally considerable increase in the number of man-hoursspent with respect to the time and man-hour requirements of the actualmaintenance intervention. Such an extension is hardly compatible withthe productivity requirements placed on such machines, which aredesigned and made for heavy-duty operation, i.e. so as to be able tooperate in a substantially continuous manner.

Based on the above considerations, it is therefore a main purpose of thepresent invention to provide a type of stationary half-mold which isadapted to do away with the above described drawbacks, is capable ofbeing easily implemented using readily available and, therefore,cost-effective materials and techniques, and is further easy, reliableand safe to use.

Such an aim of the present invention, along with further featuresthereof, is reached in a type of mold that is made and operates asrecited in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take the form of a preferred, although notsole, embodiment, such as the one that is described in detail andillustrated below by way of non-limiting example, with reference to theaccompanying drawings, in which:

FIGS. 1 and 2 represent the Prior Art described above;

FIG. 3 is a vertical cross-sectional view of a half-mould according tothe present invention, with a base plate, nozzle-carrying plate andcavity-carrying plate thereof in a mutually aligned arrangement, butseparated from each other;

FIG. 4 is the same view as the one appearing in FIG. 3, but with theplates connected to each other in their operating state;

FIG. 5 is a view of the base plate as seen from section A—A of FIG. 3;

FIG. 6 is a view of the base plate as seen from section B—B of FIG. 4;and

FIG. 7 is a view of the nozzle-carrying plate as seen from section C—Cof FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although reference will be made in the following description to avertical-drive, vertically extending machine, in which the stationaryhalf-mold has its cavities facing upwards, it will be appreciated thatthe present invention shall be understood as also applying to and beinguseful for any other kind of molding machines, in particular also theso-called horizontal-drive ones, in which the moving half-mold moveswith a horizontal motion.

With reference to the above listed FIGS. 3 to 7, the component partsthat are similar or correspond to the component parts illustrated inFIGS. 1 and 2 are indicated with the same reference numerals, forreasons of greater comprehension and comparative convenience.

A half-mold adapted to be used to produce preforms of plastic materialcomprises, as usual, the afore mentioned three plates along withcorresponding resistive elements 6 and 7, as well as the nozzles 5.

The base plate 1 is provided with a housing 15 that is open upwards and,therefore, given the type of example described here, towards thenozzle-carrying plate 2. The housing 15 is delimited outwardly by atleast a kind of shoulder 16.

The base plate 1 is further provided, along an upper edge 20 of theshoulder 16 thereof, and therefore opening towards the respectivenozzle-carrying plate, with a recess 21 passing through from the housing15 inside the base plate, in which there is arranged the hot runner 4,to the outside of the base plate.

The half-mould further comprises, according to the present invention, aplurality of electric conductor leads 19, each one of which connects arespective resistive element 6 of the hot runner to a respectiveexternal terminal clamp connected to a power supply source (not shown).

These electric conductor leads 19 are partly housed in the recess 21that enables them to be able to be removed from the base plate, withoutany need for them to be disconnected from the hot runner, by simplylifting them out of the through-passing recess.

The nozzle-carrying plate 2 is in turn provided with a plurality ofelectric conductor leads 22 connecting respective resistive elements 7to an external power supply source (not shown).

In an advantageous manner, in order to enable the nozzle-carrying plate2 to be displaceable with respect to the base plate 1, i.e. removabletherefrom, the electric conductor leads 22 are connected externally toan appropriate connector 23 arranged on an outer side of the samenozzle-carrying plate 2, as illustrated in FIGS. 4 and 5, in such amanner as to ensure that the connector is able to be readily coupledwith a further connector 24 which the power-supply leads for theenergization of the resistive elements 7 are connected to.

Furthermore, it proves equally advantageous if the electric conductorleads 19 are connected externally to an appropriate respective connector25 arranged on an outer side of the same base plate 1, as illustrated inFIGS. 4, 5 and 7, in such a manner as to ensure that the connector 25 isable to be readily coupled with a further connector 26 which thepower-supply leads for the energization of the resistive elements 6associated with the hot runner 4 are connected to.

A suitable improvement lies in providing in the nozzle-carrying plate 2a through-slot 27 having at least a side thereof opening outwardly,preferably upwards as shown in FIGS. 3, 4 and 7, in which the electricconductor leads 22 may be inserted throughout the distance covered bythem from the resistive elements 7 and the connector 23.

The provision of such a through-slot enables in fact the connector 23,the related electric conductor leads 22 and the respective resistiveelements 7 to be pulled out with a single operation, without any needarising for the said component parts to be disconnected from each other.

The operating modalities and the advantages of the present inventionwill at this point be apparent to all those skilled in the art. In fact,whenever a circumstance occurs or a need whatsoever arises, owing towhich access has to be gained to the hot runner 4 or the nozzles 5, itwill be sufficient for the three aforementioned plates to bemechanically separated from each other, as illustrated in FIG. 3, inorder to readily gain free access to the hot runner or nozzles, withoutit being necessary for individually disconnecting the electric conductorleads 19 and 22 from and, when re-assembling, individually re-connectingthe electric conductor leads 19 and 22 to, the respective terminalclamps of the respective resistive elements 6 and 7.

It will be also appreciated how, with this solution making use ofdistinct connectors 23 and 25 arranged on the outer surface of the baseplate 1 and the nozzle-carrying plate 2, respectively, the possibilityis also given for the nozzle-carrying plate to be most easily andquickly removed and replaced with a nozzle-carrying plate havingdifferent characteristics, as far as the latter is of course providedwith the same kind of mechanical and electric interface elements.

In full accordance with the aims of the present invention, a half-moldhas in this way therefore been implemented which enables the operatingflexibility and productivity of the whole plant to be significantlyboosted and the machine downtime to be considerably reduced, along withthe working time required to both replace the nozzle-carrying plates andcarry out any required maintenance work on the hot runner and theassociated functional parts.

What is claimed is:
 1. An injection half-mold, comprising: a base plate;a nozzle-carrying plate; a cavity-carrying plate; a hot runner; aplurality of resistive elements associated with said hot runner, saidplurality of resistive elements being externally connected to a powersupply source by a respective plurality of electric conductor leads thatare connected to an external connector; a plurality of nozzles arrangedand supported in said nozzle-carrying plate; and a plurality ofresistive elements heating respective said nozzles, said plurality ofresistive elements being contained in said nozzle-carrying plate andbeing connected to a power supply source by a respective plurality ofelectric conductor leads; wherein at least a portion of said pluralityof electric conductor leads of said resistive elements of saidnozzle-carrying plate is contained in the body of said nozzle-carryingplate, from which said plurality of electric conductor leads of saidresistive elements of said nozzle-carrying plate extend to outside ofsaid nozzle-carrying plate to be connected to a terminal clamp of apower supply connector; and wherein said nozzle-carrying plate isadapted to be removed and displaced away from said hot runner withoutdisconnecting said plurality of electric conductor leads of saidresistive elements of said nozzle-carrying plate or connections betweensaid plurality of electric conductor leads and said resistive elementsof said nozzle-carrying plate.
 2. The half-mold of claim 1, wherein:said hot-runner is contained in a housing provided in said base plate,said housing being capable of being closed by said nozzle-carryingplate; and said housing is delimited by at least a shoulder, saidshoulder having a recess provided in correspondence with a side of saidbase plate facing said nozzle-carrying plate, and said recess beingadapted to house said plurality of electric conductor leads of saidresistive elements of said hot runner such that said plurality ofelectric conductor leads pass from an interior of said recess to a zoneoutside of said base plate.
 3. The half-mold of claim 2, wherein saidexternal connector is on an outer surface of said base plate.
 4. Thehalf-mold of claim 3, wherein said power supply connector is on an outersurface of said nozzle-carrying plate.
 5. The half-mold of claim 4,wherein said nozzle-carrying plate has a through-slot having at least aside thereof opening towards either said cavity-carrying plate or saidnozzle-carrying plate, said through-slot being adapted to house saidportion of said plurality of electric conductor leads that extends fromsaid resistive elements to said terminal clamp.
 6. An injectionhalf-mold, comprising: a base plate; a nozzle-carrying plate adapted tobe assembled with said base plate; a cavity-carrying plate adapted to beassembled with said nozzle-carrying plate; a hot runner provided in saidbase plate, said hot runner having a plurality of resistive elementsthat are connected to an external power source by a plurality ofelectric conductor leads, and said base plate having a recess throughwhich said electric conductor leads extend, such that said electricconductor leads can be removed from said base plate withoutdisconnection of said electric conductor leads from said resistiveelements of said hot runner; and a plurality of nozzles supported insaid nozzle-carrying plate, said nozzles having a plurality of resistiveelements connected to a power supply by a plurality of electricconductor leads, and said electric conductor leads of said nozzlesextending outside of said nozzle-carrying plate to a connector through arecess in said nozzle carrying plate, such that said nozzle-carryingplate can be removed from said hot runner without disconnecting saidplurality of electric conductor leads of said nozzle-carrying plate fromsaid connector or connections between said plurality of electricconductor leads and said resistive elements of said nozzle-carryingplate.
 7. An injection half-mold, comprising: a base plate; anozzle-carrying plate; a cavity-carrying plate; a hot runner containedin a housing provided in said base plate, said housing being capable ofbeing closed by said nozzle-carrying plate; a plurality of resistiveelements associated with said hot runner, said plurality of resistiveelements being externally connected to a power supply source by arespective plurality of electric conductor leads that are connected toan external connector; a plurality of nozzles arranged and supported insaid nozzle-carrying plate; and a plurality of resistive elementsheating respective said nozzles, said plurality of resistive elementsbeing contained in said nozzle-carrying plate and being connected to apower supply source by a respective plurality of electric conductorleads; wherein at least a portion of said plurality of electricconductor leads of said resistive elements of said nozzle-carrying plateis contained in the body of said nozzle-carrying plate, from which saidplurality of electric conductor leads of said resistive elements of saidnozzle-carrying plate extend to outside of said nozzle-carrying plate tobe connected to a terminal clamp of a power supply connector; andwherein said nozzle-carrying plate is adapted to be removed anddisplaced away from said hot runner without disconnecting said pluralityof electric conductor leads of said resistive elements of saidnozzle-carrying plate or connections between said plurality of electricconductor leads and said resistive elements of said nozzle-carryingplate.